Plug for plug rolling

Abstract

The plug is assembled from three parts held against the mandrel by a tie rod which is screwed into the front and guiding part. A spacer is keyed to the latter part as well as to the tie rod, whereby tie rod keying is provided though flat surface portions interrupting the cylindrical surface portions of the spacer bore and the tie rod, while the guiding part and spacer are mutually keyed through axially aligned square portions and a clip thereon.

We claim: 
     
       1. Plug for plug rolling mills to be connected to a mandrel and having a first plug element, being the primary working plug in abutment with the mandrel, an intermediate plug element, and a guiding plug element, the improvement comprising:   a tie rod threadedly received with one end by the guiding plug element and having a cone for connection to a mandrel insert on the other end, the first and intermediate plug elements being traversed by the tie rod;   resilient means interpositioned between the first and intermediate plug elements through which the latter urges the former against the mandrel insert;   a spacer interposed and in abutment with the intermediate and the guiding plug elements;   first means for preventing relative angular displacement between the guiding and the intermediate plug elements; and   second means for preventing angular displacement of the guiding plug element relative to the tie rod, so that by operation of the first and second means the guiding element is prevented from unscrewing.   
     
     
       2. Plug as in claim 1, wherein the first means includes a square clip, the guiding and intermediate plug elements having axially alignable keying surfaces for engagement with said clip. 
     
     
       3. Plug as in claim 1, wherein the second means includes engaging keying surfaces of the tie rod and the spacer.